This invention relates to devices for automatically actuating a controlled unit, such as a valve, in response to seismic forces or other shock forces of predetermined magnitude.
Various types of devices have been proposed in the past in which a weight is displaceable by seismic or other shock forces relative to a support structure and functions by such relative displacement to actuate a mechanism for operating a controlled unit, as for instance to close a valve when an earthquake occurs. One such device is shown in U.S. Pat. No. 4,185,507 issued Jan. 29, 1980 to Domyan, in which the support structure is a pedestal having an upper surface upon which the actuating weight is located, with the coacting mechanism including a tube disposed about the pedestal and adapted to be actuated downwardly by the weight when it is displaced laterally from its normal position on the pedestal.